Swash plate gas compressor

ABSTRACT

A gas compressor comprises substantially identical cylinder block heads having interconnected fluid passages cast therein. A plurality of pistons, reciprocally mounted in the cylinder blocks, each have a thrust bearing shoe adjustably mounted thereon. A swash plate reciprocates each piston through a ball bearing which engages a respective bearing shoe.

United States Patent 1 Wahl, J1.

[ 1 July 31, 1973 SWASH PLATE GAS COMPRESSOR [75] Inventor: Thomas V. Wahl, In, North Pekin,

Ill.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Dec. 27, 1971 211 Appl. No.: 212,083

[52] U.S. Cl. 417/269 [51] Int. Cl F041) l/l2 [58] Field of Search 417/269, 271;

[56] References Cited UNITED STATES PATENTS 3,215,341 11/1965 Francis 417/269 3,352,485 11/1967 Niki et al 417/260 3,557,664 lll971 Akaike 417/269 3,057,545 10/1962 Ransom et a1 417/269 3,319,878 5/1967 Steinhagen et al. 417/269 Primary ExaminerWilliam L. Freeh Assistant Examiner-Gregory La Pointe Attorney-Paul S. Lempio et a1.

[57] ABSTRACT A gas compressor comprises substantially identical cylinder block heads having interconnected fluid passages cast therein. A plurality of pistons, reciprocally mounted in the cylinder blocks, each have a thrust bearing shoe adjustably mounted thereon. A swash plate reciprocates each piston through a ball bearing which engages a respective bearing shoe.

11 Claims, 5 Drawing Figures Patented July 31, 1973 4 Sheets-Shut l INVENTORS THGMAS WAHL.JR.

Patented July 31, 1973 4 Shoots-Sheet 1:

NE E

INVENTORS THOMAS V. WAHL.JR.

BY 7 y 72/ QLQZRZEYS Patented July 31, 1973 3,749,523

4 Sbeat8-Shoet 3 INVENTORS THOMAS V. WAHL. JR.

ww 7% mm s Patented July 31, 1973 3,749,523

4 Shoots-Shut 4 INVENTORS THOMAS V. WAHLJR.

'29-, W y vw w -f" AT TORNEYS SWASII PLATE GAS COMPRESSOR BACKGROUND OF THE INVENTION This invention relates to a swash plate compressor particularly adapted for supplying compressed gas to a gas turbine.

Commercial gas turbines oftentimes utilize natural gas as a fuel. The gas normally requires precompression prior to its delivery to the turbine for efficient combustion purposes. Conventional swash plate compressors oftentimes require very close machining tolerances and the replacement of worn thrust bearing shoes thereof when undue piston end play induces inefficient turbine operation. In addition, the compressed, exhausted gases are generally communicated to the turbine in a non-cooled state and the compressor housing requires extensive machining and related fabrication.

SUMMARY OF THE INVENTION An object of this invention is to overcome the above, briefly described problems by providing a noncomplex, economical, and efficient swash plate compressor comprising means for adjusting its thrust bearing shoes, positioned between each piston and a swash plate, to precisely adjust the pistons to produce equal operating clearances at opposite ends thereof.

In addition, the intake passages to the compression chambers of the compressor are preferably arranged in surrounding heat exchange relationship with respect to the exhaust passages thereof to cool the exhausted, compressed gases prior to their communication to a gas turbine, for example. Also, substantially identical cylinder blocks and heads preferably comprise the compressor housing.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects of this invention will become apparent from the following description and accompanying drawings wherein:

FIG. 1 is a longitudinal, sectional view of a gas compressor taken in the general direction of arrows l--I in FIGS. 3 and 4;

FIG. 2 is another longitudinal, sectional view of the gas compressor, taken in the general direction of arrows II-II in FIGS. 3 and 4;

FIG. 3 is an exploded, isometric view of the gas compressor;

FIG. 4 is a cross sectional view of the gas compressor, taken in the direction of arrows IVIV in FIG. 1; and

FIG. 5 is an enlarged cross sectional view of an oil pump, employed in a lubrication system for the gas compressor, taken in the direction of arrows V-V in FIG. 1.

DETAILED DESCRIPTION Referring to FIGS. 1-3, the housing ofa gas compressor comprises a pair of substantially identical and abutting cylinder blocks 1 1, each having an intake reed plate 12, a spacer plate 13 and an exhaust reed plate 14, mounted on an outboard end thereof. The cylinder blocks and plates are clamped together as a unit, along with substantially identical front and rear cylinder heads 15 and 15', respectively, by 14 double-end rods 16. Since the two halves of the gas compressor are substantially identical, like numerals are used to depict corresponding constructions.

Four cylinder bores 17 are formed in each cylinder block to reciprocally mount pistons 18 therein. As shown in FIG. 1, each axially opposed pair of pistons are interconnected by a bridging connection 19 to be reciprocated simultaneously by a swash plate 20. The swash plate is keyed at 21 to a shaft 22 which may be selectively rotated by a drive input shaft 23.

Each piston has a cup member 24 threadably mounted thereon to adjust the cup member axially between the piston and the swash plate to precisely set the distance between each piston and a respective reed plate 12. A serrated ring 25 is secured to the cup member to provide lock means for positively locking the member in place by its releasable engagement with a cantilevered, resilient spring member 26, secured to the piston. A ball bearing 27 is seated in the cup member and also seats in a bearing shoe or second cup member 28, in slidable contact with the swash plate, to provide drive means for transmitting axial movement from the swash plate to the piston.

It can thus be seen that selective adjustment of each pair of axially opposed cup members 24 will effect equal clearances at the opposite ends of therespective pistons. During operation loads occasioned by rotation of the swash plate are readily counteracted by means of axially spaced collar bearings 29 and thrust bearings 29a.

The natural gas to be pressurized is communicated to an intake manifold 30 via an inlet 31 (FIG. 3) of intake passage means. The gas then flows to annular chambers 32 and through ports 33 and intake reeds 34 into compression chambers 17 (FIG. 2). When the gas pressure exceeds a predetermined level in a chamber, upon the compression stroke 35 of a respective piston, an exhaust reed 36 opens to permit the pressurized gas to exit therefrom and through exhaust passage means. In particular, the pressurized gas then flows through a port 37, formed in spacer plate 13, into an annular chamber 38 and through a passage 39 which communicate with a discharge manifold 40. Outlet 41 of the manifold may be connected to the fuel supply for a gas turbine engine, for example. It should be noted that inlet chambers 32 and ports 33 are disposed in surrounding, heat exchange relationship with outlet chamber 39, and passages 38 for gas cooling purposes.

Referring to FIG. 3, the intake reeds 34 are cut into a plate 12 to be radially disposed about the longitudinal axis of shaft 22. Each reed comprises an inner leg portion 42 connected to a main body thereof and an outer tab portion 43 which seats in a mating, arcuate cutout formed in the intake reed plate to precisely control the opening and closing of the intake reed. The main body portion of the intake reed will normally be urged into masked, sealing relationship with an underlying port 33 prior to its opening upon movement of the piston away therefrom.

The exhaust reeds 36 are also radially disposed about the longitudinal axis of shaft 22 and are cantilevered on an exhaust reed plate 14 to normally mask underlying ports 37. The maximum opening of each exhaust reed is limited by a fixed stop member 44. The stop members are radially disposed on a star-like member secured between the housing and the exhaust reed plate (FIG. 1).

Referring to FIGS. 1 and'5, an oil lubrication system for the compressor comprises an oil sump 45, cast integrally in the cylinder blocks. A line 46 communicates the sump with an oil pump 47 driven by shaft 22. Oil is pumped through a rifle passage 48 formed in the shaft to communicate oil to collar bearings 29 via ports 49 and to thrust bearings 30 and to swash plate 20 via ports 50.

Oil is returned to the sump from the swash plate chamber via slots 51 and from the cylinder heads via passages 52. Lubricating oil temperature is preferably maintained at a suitably low level by means of a recirculated coolant. The coolant is communicated to inlets 53 (FIGS. 1 and 3) and is circulated through passages 54 and to outlets 55.

What is claimed is:

l. A compressor comprising a housing, a swash plate mounted for rotation about a longitudinal axis in said housing, at least one piston reciprocally mounted in a cylinder bore formed in said housing for movement in the direction of said axis, and drive means drivingly connecting said swash plate to said piston, including adjustment means, comprising a cup member threadably mounted on said piston and disposed between said swash plate and said piston, for adjusting the axial distance between said swash plate and said piston.

2. The invention of claim 1 wherein said adjustment means further comprises lock means for releasably locking said cup member in a selected rotative position on said piston.

3. The invention of claim 2 wherein said lock means comprises a serrated ring secured to said cup member and a resilient spring member secured to said piston to normally engage a serration of said ring.

4. The invention of claim 1 wherein said drive means further comprises a second cup member in slidable contact with said thrust plate and a ball bearing seated in said cup members.

5. The invention of claim 1 further comprising a second piston axially opposed to said first-mentioned piston and a bridging connection interconnecting said pistons for effecting simultaneous movement thereof upon rotation of said swash plate.

6. The invention of claim 5 wherein said compressor comprises a plurality of said interconnected pistons reciprocally mounted in said housing in radial disposition about said axis.

7. The invention of claim 1 wherein said housing comprises two substantially identical and abutting cylinder blocks, each having a plurality of said pistons mounted therein, and substantially identical cylinder heads, each attached to an end of a respective cylinder block, and further comprising passage means, fonned entirely within said housing, for communicating fluid to said cylinder bores and for further communicating said fluid from said cyinder bores, exteriorly of said compressor.

8. The invention of claim 7 further comprising intake and exhaust reed plates and an intermediate spacer plate all secured between each adjacent cylinder block and head, each of said reed plates comprising a normally closed reed valve exposed to each of said cylinder bores.

9. The invention of claim 8 wherein said passage means comprise means forming intake chambers and ports positioned to communicate fluid into said cylinder bores and means forming exhaust chambers and ports, substantially surrounded by said intake chambers and ports, positioned to communicate compressed fluid out of said cylinder bores.

10. The invention of claim 1 wherein said swash plate is secured to a shaft rotatably mounted by spaced bearings in said housing and further comprising lubricating means for communicating lubricant to said bearings.

11. The invention of claim 1 further comprising means for circulating a coolant through said housing in close proximity to said piston. 

1. A compressor comprising a housing, a swash plate mounted for rotation about a longitudinal axis in said housing, at least one piston reciprocally mounted in a cylinder bore formed in said housing for movement in the direction of said axis, and drive means drivingly connecting said swash plate to said piston, including adjustment means, comprising a cup member threadably mounted on said piston and disposed between said swash plate and said piston, for adjusting the axial distance between said swash plate and said piston.
 2. The invention of claim 1 wherein said adjustment means further comprises lock means for releasably locking said cup member in a selected rotative position on said piston.
 3. The invention of claim 2 wherein said lock means comprises a serrated ring secured to said cup member and a resilient spring member secured to said piston to normally engage a serration of said ring.
 4. The invention of claim 1 wherein said drive means further comprises a second cup member in slidable contact with said thrust plate and a ball bearing seated in said cup members.
 5. The invention of claim 1 further comprising a second piston axially opposed to said first-mentioned piston and a bridging connection interconnecting said pistons for effecting simultaneous movement thereof upon rotation of said swash plate.
 6. The invention of claim 5 wherein said compressor comprises a plurality of said interconnected pistons reciprocally mounted in said housing in radial disposition about said axis.
 7. The invention of claim 1 wherein said housing comprises two substantially identical and abutting cylinder blocks, each having a plurality of said pistons mounted therein, and substantially identical cylinder heads, each attached to an end of a respective cylinder block, and further comprising passage means, formed entirely within said housing, for communicating fluid to said cylinder bores and for further communicating said fluid from said cyinder bores, exteriorly of said compressor.
 8. The invention of claim 7 further comprising intake and exhaust reed plates and an intermediate spacer plate all secured between each adjacent cylinder block and head, each of said reed plates comprising a normally closed reed valve exposed to each of said cylinder bores.
 9. The invention of claim 8 wherein said passage means comprise means forming intake chambers and ports positioned to communicate fluid into said cylinder bores and means forming exhaust chambers and ports, substantially surrounded by said intake chambers and ports, positioned to communicate compressed fluid out of said cylinder bores.
 10. The invention of claim 1 wherein said swash plate is secured to a shaft rotatably mounted by spaced bearings in said housing and further comprising lubricating means for communicating lubricant to said bearings.
 11. The invention of claim 1 further comprising means for circulating a coolant through said housing in close proximity to said piston. 